Question

Can someone explain why these are different on the graph line?

Answer 1

Explanation:

typically, we use the curved parentheses the denote an open interval, so we don't include the extreme values.

for example, the interval (1, 2) will not include 1 and 2. think of it as using the < and > symbols.

on the other hand, we have the boxed parentheses which denote a closed interval, which includes the extreme values.

so, for example [1, 2] would include 1 and 2. think of it as using

`\leqslant and \geqslant`

signs.

in fact, we can use these signs to explain the intervals better:

`(a, b) \implies a < x < b\\ [a, b] \implies a \leq x \leq b`

personally, I've seen people use black dots to denote closed intervals and white dots to denote open intervals more often, they mean the same.